Method For Manufacturing Plated Resin Molded Article

ABSTRACT

The present invention provides a method for manufacturing plated resin molded article having strong adhesion of plating and giving beautiful appearance. Specifically, it provides a method for manufacturing plated resin molded article having the steps of: contact-treating a thermoplastic resin molded article using an acid or base free from heavy metal; treating the contact-treated thermoplastic resin molded article by a catalyst imparting liquid; forming an electrically conductive layer on the surface of the thermoplastic resin molded article using a direct plating method; and applying electroplating to the electrically conductive layer; without applying the step of etching by an acid which contains heavy metal.

TECHNICAL FIELD

The present invention relates to a method for manufacturing plated resinmolded article which has strong adhesion of plating.

BACKGROUND ART

Resin molded articles such as an ABS resin and a poly amide resin havebeen used as automobile parts for the purpose of reducing the weight ofan automobile, and plating such as copper or nickel is carried out onthe resin molded articles in order to give a upscale image and a senseof beauty.

When the plating is carried out on resin molded articles such as an ABSresin, an etching step of roughing the surface of the resin moldedarticles is conventionally essential to enhance the adhering strengthafter the removal step of fat. For example, when an ABS resin moldedarticle and a polypropylene molded article are plated, a bath of chromicacid (a mix solution of chromium (III) oxide and sulfuric acid) is usedafter the removal step of fat, and an etching treatment is required tobe carried out at 65 to 70° C. for 10 to 15 minutes. Accordingly,poisonous hexa-valent chromic acid ion is contained in waste water.Therefore, a treatment of neutrally precipitating after reducing thehexa-valent chromic acid ion to a tri-valent ion is essential, whichcreates problems in wastewater treatment.

Considering safety during a work at a spot and an influence toenvironment due to waste water thus, it is desirable not to carry out anetching treatment using the chromium bath, but in that case, there is aproblem that the adhering strength of a plating layer to a moldedarticle which is obtained by an ABS resin and the like cannot beenhanced.

Inventions disclosed in JP-A 2003-82138 and JP-A 2003-166067 aresuperior in obtaining plated resin molded articles having high platingstrength without using the chromic acid etching. They have, however, anissue of consuming large man-hours in the manufacturing process (platingstep).

JP-A 5-239660 and WO 98/45505 (U.S. Pat. No. 3,208,410) describe the useof direct plating method during the course of plating on the surface ofresin molded article. According to the Experimental Example 1 of JP-A5-239660, however, a pretreatment of surface roughening with pumice isapplied, thus it is difficult to manufacture a resin molded articlehaving beautiful appearance. Since WO 98/45505 (U.S. Pat. No. 3,208,410)adopts chromic acid etching, it cannot solve the problems ofconventional technologies.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a method formanufacturing plated resin molded article which can eliminate theetching treatment by chromic acid and the like, which has strongadhesion between the resin molded article and the plating layer, andwhich provides beautiful appearance.

The first aspect of the present invention is to provide a method formanufacturing plated resin molded article comprising the steps of:contact-treating a thermoplastic resin molded article using an acid orbase free from heavy metal; treating the contact-treated thermoplasticresin molded article by a catalyst imparting liquid; forming anelectrically conductive layer on the surface of the thermoplastic resinmolded article using a direct plating method; and applyingelectroplating to the electrically conductive layer; without applyingthe step of etching by an acid which contains heavy metal.

DETAIL DESCRIPTION OF THE INVENTION

The second aspect of the present invention is to provide the method formanufacturing plated resin molded article according to claim 1, whereinthe direct plating method comprises the step of forming an electricallyconductive layer on the surface of a thermoplastic resin molded articleusing a selector liquid which contains a metallic compound, a reducingcompound and a metallic hydroxide.

The third aspect of the present invention is to provide the method formanufacturing plated resin molded article according to claim 1 or 2,wherein the thermoplastic resin molded article contains a polyamide.

The fourth aspect of the present invention is to provide the method formanufacturing plated resin molded article according to claim 1 or 2,wherein the thermoplastic resin molded article further contains asubstance which has a solubility (23° C.) in water of 300 g/100 g orless.

According to the manufacturing method of the present invention, use ofthe direct plating method allows decreasing the man-hours compared withthe inventions disclosed in JP-A 2003-82138 and 2003-166067, andeliminates the toxic reducing agent such as formalin.

The description for individual steps is given below. Regarding the stepsdescribed below, a single step may be divided into two or more ofsub-steps, and two or more of steps may be integrated into a singlestep. Furthermore, at needed, a known step in the plating method may beadded as described below.

First, the degreasing treatment is applied to a thermoplastic resinmolded article which is formed into a shape suitable for the use using aknown method such as injection molding.

The degreasing treatment is conducted using an aqueous solution ofsurfactant containing an alkali such as sodium hydroxide or sodiumcarbonate, or an acid such as sulfuric acid or carboxylic acid. Afterthe degreasing treatment, the present invention allows to move tosucceeding step without need of the etching step using chromic acid andthe like, as the surface-roughening treatment in order to increase theadhesion of plating layer, and without need of physicalsurface-roughening treatment (for example, a treatment of rubbing thesurface with pumice, as disclosed in JP-A5-239660).

In the next step, the thermoplastic resin molded article is subjected tocontact-treatment by an acid or base free from heavy metal (metal suchas chromium and manganese). The degreasing treatment as the precedingstep may be eliminated, and the contact-treatment may be adopted as thefirst treatment step.

The acid free from heavy metal may be hydrochloric acid, phosphoricacid, sulfuric acid, or an organic acid such as acetic acid, citric acidor formic acid. The base free from heavy metal may be a hydroxide ofalkali metal or alkali earth metal, such as sodium hydroxide, potassiumhydroxide, calcium hydroxide or magnesium hydroxide.

A concentration of the acid or base free from heavy metal differs withthe kind. For the case of hydrogen chloride, however, a preferrednormality is in a range from 1.5 to 3.5. For the case of hydrochloricacid, a preferred normality is in a range from 1.8 to 3.5, and morepreferably from 2 to 3. For other acids or bases, their concentrationsmay be selected so as the surface of the thermoplastic resin after thetreatment, (which can be determined by, for example, a scanning electronmicroscope (SEM)), to become equivalent to that of the hydrogen chloridetreatment.

For instance, the treatment in the step can use a method of immersingthe thermoplastic resin-molded article into an acid or base free fromheavy metal. Specifically there is applied a method immersing thearticle in an acid or base free from heavy metal at a liquid temperaturein a range from 10° C. to 80° C. for a period from 0.5 to 20 minutes.When hydrochloric acid with a normality in a range from 1.5 to 3.5 isused, the article may be immersed in an aqueous solution of hydrochloricacid with the above concentration range at a temperature ranging from20° C. to 60° C. for a period from 1 to 10 minutes.

Then, the step of treating with a catalyst-providing liquid is given tothe thermoplastic resin-molded article after the preceding step. Thestep is a known one, and it is preferable to give a step ofwater-washing before and after the step.

The catalyst-providing liquid may be a known one. Examples of thecatalyst-providing liquid are the one containing a catalyst metal, a tincompound and an acid, and, at needed, containing other components.

The catalyst may be a known one. Examples of the catalyst are a platinumcompound (platinum chloride salt, and the like), a gold compound (goldsulfite salt, and the like), a palladium compound (palladium chloride,palladium sulfate, and the like), a silver compound (silver nitrate,silver sulfate, and the like). A preferable amount of the catalyst is ina range from 100 to 500 mg/L as metal.

Applicable tin compound includes tin(II) chloride and tin(II) sulfate. Apreferable use amount of the tin compound is in a range from 10 to 50g/L as tin, and 50 to 120 times (mass basis) the amount of the catalystmetal.

The acid is hydrochloric acid, sulfuric aid, or a mixed acid ofhydrochloric acid and sulfuric acid. Alternatively, they may be mixedwith sodium chloride. The acid is adjusted so as the pH of thecatalyst-providing liquid to become around 1.

A preferable catalyst-providing liquid is the one which contains apalladium compound as the catalyst, tin(II) chloride as the tincompound, and hydrochloric acid as the acid. The treatment in the stepcan adopt a method of immersing the thermoplastic resin-molded articleinto a catalyst-providing liquid at room temperature for a periodapproximately from 1 to 10 minutes.

In the next step, an electrically conductive layer is formed on thesurface of the thermoplastic resin molded article using the directplating method. The direct plating method is a known technique, and isdisclosed in JP-A 5-239660, WO 98/45505 (U.S. Pat. No. 3,208,410), JP-A2002-338636 (Paragraph No. 5), and others. During the step, a platingliquid called the “selector liquid” is used, thus forming a very thinelectrically conductive layer compared with the plating layer(electrically conductive layer) formed by the conventionally and widelyusing chemical plating.

Use of the direct plating method is superior in the following items tothe manufacturing method of the inventions of JP-A 2003-82138 and2003-166067, containing the electroless plating method (chemical platingmethod).

(1) Safety is high because of strong reducing power of formalin and thelike and of free from toxic substances as seen in the case ofelectroless plating method (chemical plating method).(2) Manufacturing time can be decreased and manufacturing cost can bedecreased because of not-need of activation step after thecatalyst-providing step, thus decreasing the man-hours.(3) Although the electroless plating method (chemical plating method)needs further pluralities of steps before the electroplating, the directplating method allows immediately entering the electroplating so thatthe man-hours can be decreased, the manufacturing time can be decreased,and the manufacturing cost can be decreased.(4) Electroless plating method (chemical plating method) results indeposition of plating also on the jigs using in the plating, thus thereplacement of jigs becomes necessary. Direct plating method, however,plating very little deposits on the jigs.

Applicable selector liquid includes a liquid containing a metalliccompound, a reducing compound, and a metallic hydroxide.

A preferred metallic compound is a copper compound. Examples of thecopper compound are copper(II) sulfate, copper chlorides, coppercarbonates, copper oxides and copper hydroxides. The content of coppercompound is preferably in a range from 0.1 to 5 g/L as copper, and morepreferably from 0.8 to 1.2 g/L.

The reducing compound does not include the one having strong reducingpower, such as formalin and phosphinic acid, which are widely used inknown electroless plating (chemical plating), and is the one having weakreducing power compared with those given above. Examples of the reducingcompound include the following:

tin(II) chloride, sodium borohydride, dimethylamine borane,trimethylamine borane, formic acid or salt thereof, alcohol such asmethanol, ethanol, propanol, ethylene glycol or glycerin, and saltthereof; and

reducing saccharide such as glucose, sorbite, cellulose, sucrose,mannite or gluconolactone. The content of succharide is preferably in arange from 3 to 50 g/L, and more preferably from 10 to 20 g/L.

Applicable metallic hydroxide includes sodium hydroxide, potassiumhydroxide and lithium hydroxide. The content of metallic hydroxide ispreferably in a range from 10 to 80 g/L, and more preferably from 30 to50 g/L.

The selector liquid can, at needed, further contain a complexing agent.Applicable complexing agent includes hydantoins and organic carboxylicacids. The hydantoins include hydantoin, 1-methylhydantoin,1,3-dimethylhydantoin, 5,5-dimethylhydantoin and allantoin. Applicableorganic carboxylic acids include citric acid, tartaric acid, succinicacid, and salt thereof. The content of complexing agent in the selectoris preferably in a range from 2 to 50 g/L, and more preferably from 10to 40 g/L.

The pH of selector liquid is preferably in a range from 10.0 to 14.0,and more preferably from 11.55 to 13.5.

Examples of the selector liquid are the plating bath described inExperimental Example 1 (C) of JP-A 5-239660, and the invention baths 1to 8 described in WO 98/45505 (U.S. Pat. No. 3,208,410). If needed,other known components may also be added to the bath.

The treatment in the step may adopt a method in which the temperature ofthe selector liquid is adjusted to a range preferably from 20° C. to 70°C., more preferably from 35° C. to 50° C., then the thermoplastic resinmolded article is immersed in the liquid for a period approximately from30 seconds to 20 minutes, preferably approximately from 3 to 5 minutes.

Since the treatment of the step forms a very thin electricallyconductive layer on the surface of the thermoplastic resin-moldedarticle, the succeeding step can directly apply the electroplating.

After that, a know method is used to conduct electroplating of copper,nickel, chromium, and the like onto the thermoplastic resin-moldedarticle on which the electrically conductive layer is formed in thepreceding step.

The thermoplastic resin molded article to which the manufacturing methodof the present invention is applied can be obtained by molding athermoplastic resin composition containing a combination of one or moreof the thermoplastic resins described below, and, at needed, othercomponents.

Although the thermoplastic resin can be arbitrarily selected among theknown ones responding to the uses, the present invention preferably usesa polyamide-based resin, a styrene-based resin, an olefin-based resin, apolyphenylene ether resin (PPE), a polyphenylene sulfone resin (PPS),and a polysulfone resin, and more preferably uses a thermoplastic resincomposition which contains a polyamide-based resin.

A preferable thermoplastic resin is the one having a water absorption(in water at 23° C. after 24 hours have passed: ISO 62) of 0.6% or more,more preferably in a range from 0.6 to 5%, and most preferably from 0.6to 2%.

If a thermoplastic resin having poor water absorption is treated by amanufacturing method containing direct plating method, the increase inthe man-hours is inevitable to attain the optimum conditions tomanufacture the resin-molded article having beautiful appearance andhigh adhesion of plating. If, however, the resin composition whichcontains a thermoplastic resin having good water absorption (also goodadsorption of metal) as described above, or a resin compositioncontaining a thermoplastic resin having good water absorption is used,the direct plating method readily forms the electrically conductivelayer, which is preferable because of decreasing the man-hours.

If a thermoplastic resin composition containing two or more of resins isused, it is preferable that the content of the thermoplastic resin whichsatisfies the above water absorption is adjusted to 30% by mass or more.

The polyamide-based resin is a polyamide resin formed from diamine anddicarboxylic acid, and a copolymer thereof. The resin may be incrystalline shape, in amorphous shape, or in a mixture thereof. Ifcrystalline shape and amorphous shape are mixed together, thecrystallinity degree is preferably 60% or less, and more preferably 40%or less.

The polyamide-based resin includes: nylon 66, polyhexamethylenesebacamide (nylon 6-10), polyhexamethylene dodecanamide (nylon 6-12),polydodecamethylene dodecanamide (nylon 1212), polymethaxylyleneadipamide (nylon MXD6), polytetramethylene adipamide (nylon 46), theirmixture, and a copolymer thereof; nylon 6/66, nylon 66/6T (6T:polyhexamethylene terephthalamide) containing 50% by mole or less of 6Tcomponent, nylon 66/6I (6I: plyhexamethylene isophthalamide) containing50% by mole or less of 6I component, copolymer of nylon 6T/6I/66 andnylon 6T/6I/610; polyhexamethylene terephthalamide (nylon 6T),polyhexamethylene isophthalamide (nylon 6I),poly(2-methylpentamethylene)terephthalamide (nylon M5T),poly(2-methylpentamthylene)isophthalamide (nylon M5I), and copolymer ofnylon 6T/6I and of nylon 6T/M5T. Other than the above, a copolymer nylonsuch as amorphous nylon is applicable. An example of the amorphous nylonis polycondensate of terephthalic acid and trimethyl hexamethylenediamine.

Other applicable polyamide-based resins are a ring-opened polymer ofcyclic lactam, a polycondensate of aminocarboxylic acid, and a copolymercomposed of these components; specifically an aliphatic polyamide resinsuch as nylon 6, poly-ω-undecanamide (nylon 11) or poly-ω-dodecanamide(nylon 12), and a copolymer thereof, a copolymer with polyamideconsisting of diamine and dicarboxylic acid, specifically nylon 6T/6,nylon 6T/11, nylon 6T/12, nylon 6T/6I/12, nylon 6T/6I/610/12, and amixture thereof.

As of these, preferable polyamide-based resins are PA (nylon)₆, PA(nylon)66 and PA (nylon)6/66.

A preferred polyamide-based resin is the one having 10 J/g or largerheat of crystal fusion, more preferably from 10 to 150 J/g, furtherpreferably from 15 to 120 J/g, specifically preferably from 20 to 100J/g, and most preferably from 25 to 90 J/g. The polyamide-based resinwhich has the heat of crystal fusion within the above range contains thecrystal portion being determined by the heat of crystal fusion and alsocontains residual amorphous portions.

By specifying the heat of crystal fusion of the polyamide-based resin tothe above range, the amorphous portion of the polyamide-based resin isseparated from the surface of the thermoplastic resin-molded article,and the function of micropores created after the separation of theamorphous portion induces the formation of the strong plating layer,which is preferable.

The heat of crystal fusion is determined by DSC observation. That is, 5to 10 mg of sample is collected from the target polyamide-based resinpellets. The sample is scanned by DSC 600E (manufactured by ShimadzuCorp.) for two times of temperature scanning under the conditions of 20°C./min of temperature-rising speed and 20° C./min oftemperature-lowering speed. The heat of crystal fusion observed in thesecond scan is adopted as the heat of crystal fusion.

Examples of the styrene-based resin are styrene and polymers ofstyrene-derivatives such as α-substitution or nucleus substitutionstyrene. There are also included copolymers composed mainly of abovemonomers and containing monomers such as vinyl compound such asacrylonitrile, acrylic acid, and methacrylic acid, and/or conjugatediene compound such as butadiene and isoprene. Examples of them arepolystyrene, high-impact polystyrene (HIPS resin),acrylonitrile-butadiene-styrene copolymer (ABS resin),acrylonitrile-styrene copolymer (AS resin), styrene-methacrylatecopolymer (MS resin) and styrene-butadiene copolymer (SBS resin).

The polystyrene-based resin may contain a styrene-based copolymer inwhich an unsaturated compound containing carboxy group is copolymerizedto increase the compatibility with polyamide-based resin. Thestyrene-based copolymer in which the unsaturated compound containingcarboxy group is copolymerized is a copolymer prepared by polymerizingan unsaturated compound containing carboxylic group with, at needed,other monomer which can copolymerized therewith, in the presence of agummy polymer. Examples of the components are:

(1) a graft polymer prepared by polymerizing a monomer containing anaromatic vinyl monomer as the essential component or a monomercontaining an aromatic vinyl compound and an unsaturated compoundcontaining carboxy group as the essential components in the presence ofa gummy polymer prepared by copolymerizing an unsaturated compoundcontaining carboxy group;(2) a graft copolymer prepared by copolymerizing an aromatic vinylcompound and an unsaturated compound containing carboxy group as theessential components in the presence of a gummy polymer;(3) a mixture of a rubber-strengthening styrene-based resin in which theunsaturated compound containing carboxy group is not copolymerized and acopolymer of a monomer containing an unsaturated compound containingcarboxy group and an aromatic vinyl compound as the essentialcomponents;(4) a mixture of the above (1) and (2), and a copolymer containing anunsaturated compound containing carboxy group and an aromatic vinylcompound as the essential compounds; and(5) a mixture of the above (1), (2), (3) and (4), and a copolymercontaining the essential component of an aromatic vinyl compound.

In above 1) to 5), the aromatic vinyl compound is preferably styrene,and the monomer copolymerizing with the aromatic vinyl compound ispreferably acrylonitrile. The content of the unsaturated compoundcontaining carboxyl group in the styrene is preferably in a range from0.1 to 8% by mass, and more preferably from 0.2 to 7% by mass.

The olefin-based resin is a polymer containing a main component ofmonomer of C2-8 olefin, which includes one or more of low-densitypolyethylene, high-density polyethylene, linear low-densitypolyethylene, polypropylene, ethylene-propylene random copolymer,ethylene-propylene block copolymer, polymethylpentene, polybutene-1, anda modified compound thereof. As of these, polypropylene andacid-modified polypropylene are preferred.

As for the polyphenylene ether resin, examples of the polyphenyleneether applicable in the present invention includespoly(2,3-dimethyl-6-ethyl-1,4-phenylene ether),poly(2-methyl-6-chloromethyl-1,4-phenylene ether),poly(2-methyl-6-hydroxyethyl-1,4-phenylene ether),poly(2-methyl-6-n-butyl-1,4-phenylene ether),poly(2-ethyl-6-isopropyl-1,4-phenylene ether),poly(2-ethyl-6-n-propyl-1,4-phenylene ether),poly(2,3,6-trimethyl-1,4-phenylene ether),poly(2-(4′-methylphenyl)-1,4-phenylene ether),poly(2-bromo-6-phenyl-1,4-phenylene ether),poly(2-methyl-6-phenyl-1,4-phenylene ether), poly(2-phenyl-1,4-phenyleneether), poly(2-chloro-1,4-phenylene ether), poly(2-methyl-1,4-phenyleneether), poly(2-chloro-6-ethyl-1,4-phenyelen ether),poly(2-chloro-6-bromo-1,4-phenylene ether),poly(2,6-di-n-propyl-1,4-phenylene ether),poly(2-methyl-6-isopropyl-1,4-phenylene ether),poly(2-chloro-6-methyl-1,4-phenylene ether),poly(2-methyl-6-ethyl-1,4-phenylene ether),poly(2,6-dibromo-1,4-phenylene ether), poly-2,6-dichloro-1,4-phenyleneether), poly(2,6-diethyl-1,4-phenylene ether) andpoly(2,6-dimethyl-1,4-phenylene ether). As of these, specificallypreferred one is poly(2,6-dimethyl-1,4-phenylene ether).

Other components being blended, at needed, in the thermoplastic resininclude a chelating agent, a water-soluble substance, a surfactantand/or a coagulant and a phosphorus-based substance from the point toincrease the adhesion between the thermoplastic resin-molded article andthe plating layer.

The chelating agent is a component to bring the metal in the platingbath to easily adhere onto the surface of the resin molded article, andthe one selected from the group given below may be used.

Aliphatic diamine such as methylene diamine, ethylene diamine,trimethylene diamine, tetramethylene diamine, pentamethylene diamine orhexamethylene diamine; aromatic diamine such as o-, m- and p-phenylenediamine, benzidine or diaminostilbene;

ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid,ethane-1-hydroxy-1,1-diphosphonic acid, and derivative thereof;phosphonic acid such as ethane hydroxy-1,1-2-triphosphonic acid,ethane-1,2-dicarboxy-1,2-diphosphonic acid, methane hdyroxyphosphonicacid, and alkali metal salt or alkanolamine salt thereof;

phosphonocarboxylic acid such as 2-phosphonobutane-1,2-dicarboxylicacid, 1-phosphonobutane-2,3,4-tricarboxylic acid, α-methylphosphonosuccinic acid, or alkali metal salt or alkanolamine salt thereof;

amino acid such as aspartic acid, glutamic acid, glycine, and alkalimetal salt or alkanolamine salt thereof;

amino polyacetate such as nitrilo triacetate, imino diacetate,ethylenediamine tetraacetate, diethylene triamine penta-acetate,grycolether diamine tetra-acetate, hydroxyethylimino diacetate,triethylenetetramine hexa-acetate, dienkolic acid, and alkali metal saltor alkanolamine salt thereof;

organic acid such as glycolic acid, diglycolic acid, oxy-disuccinicacid, carboxymethyloxy succinic acid, citric acid, malonic acid, lacticacid, tartaric acid, oxalic acid, malic acid, oxy disuccinic acid,gluconic acid, carboxymethyl succinic acid, carboxymethyl tartaric acid,α-hydroxy propionic acid, α-hydroxy isobutyric acid, and alkali metalsalt or alkanolamine salt thereof;

alkali metal salt or alkanolamine salt of aluminosilicate represented byzeolite A;

aminopoly(methylene sulfonic acid) or metal salt or alkanolamine saltthereof, or polyethylene-polyamine-poly(methylene sulfonic acid) oralkali metal salt or alkanolamine salt thereof.

Content of the chelating agent in the thermoplastic resin molded articleis preferably in a range from 0.1 to 20 parts by mass to 100 parts bymass of the thermoplastic resin, more preferably from 0.1 to 15 parts bymass, and further preferably from 0.1 to 10 parts by mass.

The water-soluble substance is a substance soluble in water independentof the solubility. Examples thereof are: polysaccharide such as starch,dextrin, pullulan, hyaluronic acid, carboxymethyl cellulose, methylcellulose, ethyl cellulose, and salt thereof; polyhydric alcohol such aspropylene glycol, ethylene glycol, diethylene glycol, neopentyl glycol,butanediol, pentanediol, polyoxyethylene glycol, polyoxypropyleneglycol, trimethylol propane, pentaerythritol, dipentaerythritol orglycerin; polyvinyl alcohol, polyacrylic acid, polymaleic acid,polyacrylamide, polyvinylpyrrolidone, polyethylene oxide, acrylicacid-maleic acid anhydride copolymer, maleic acidanhydride-diisobutylene copolymer, maleic acid anhydride-vinyl acetatecopolymer, naphthalene sulfonic acid salt-formalin condensate, and saltthereof.

As of these, preferred ones are those soluble in water with a smallsolubility. Specifically preferred ones are those having solubility (23°C.) in water of 300 g/100 g, more preferably 100 g/100 g or less, andmost preferably 10 g/100 g or less. Examples of those compounds arepentaerythritol (7.2 g/100 g) and dipentaerythritol (0.1 g/100 g orless).

The content of water-soluble compound in the thermoplastic resin moldedarticle is preferably in a range from 0.01 to 50 parts by mass to 100parts by mass of the thermoplastic resin, more preferably from 0.01 to30 parts by mass, and most preferably from 0.01 to 15 parts by mass.

Applicable surfactant and/or coagulant may be a surfactant (emulsifier)left behind in the resin after used in emulsion polymerization (ifapplied) to manufacture the thermoplastic resin, or may be the oneseparately added to the thermoplastic resin if the manufacture methodsuch as bulk polymerization which does not use emulsifier is applied.

The surfactant and/or solidifier include the one used in the emulsionpolymerization of resin, and the one other than used in the emulsionpolymerization. A preferable surfactant includes anionic surfactant,cationic surfactant, nonionic surfactant and amphoteric surfactant.

Examples of these surfactants are: anionic surfactant such as fatty acidsalt, resin acid salt, alkylsulfate, alkylbenzene sulfonate,alkyldiphenylether sulfonate, polyoxyethylene alkylether sulfonateester, sulfosuccinic acid diester salt, α-olefinsulfuric acid ester saltor α-olefin sulfonate; cationic surfactant such as mono- ordi-alkylamine or polyoxyethylene additive thereof, mono- or di-longchain alkyl quaternary ammonium salt; nonionic surfactant such asalkylglucoside, polyoxyethylene alkyl ether, polyoxyethylene alkylphenylether, sucrose fatty acid ester, sorbitan fatty acid ester,polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acidester, polyoxyethylene propylene block copolymer, fatty acidmonoglyceride or amine oxide; and amphoteric surfactant such ascarbobetaine, sulfobetaine or hydroxysulfobetaine.

The content of surfactant and/or coagulant in the thermoplastic resinmolded article is preferably in a range from 0.01 to 10 parts by mass to100 parts by mass of the thermoplastic resin, more preferably from 0.01to 5 parts by mass, and most preferably from 0.01 to 2 parts by mass.

The phosphorus based compound is a component to increase the adhesion ofplating, and one or more of the followings may be used.

Condensate phosphoric acid ester such as triphenyl phosphate, tricredilphosphate, trixylenyl phosphate, tris(isopropylphenyl)phosphate, tris(o-or p-phenylphenyl)phosphate, trinaphtyl phosphaate, credil diphenylphosphate, xylenyl diphenyl phosphate, diphenyl(2-ethylhexyl)phosphate,di(isoproplylphenyl)phenyl phosphate, o-phenylpyhenyl dicresilphosphate, tris(2,6-dimethylphenyl)phosphate, tetraphenyl-m-phenylenediphosphate, tetraphenyl-p-phenylene diphosphate, phenylresorcin-polyphosphate, bisphenol A-bis(diphenylphosphate), bisphenolA-polyphenyl phosphate or dipyrocatechol hypodiphosphate;

Fatty acid-aromatic phosphoric acid ester including ortho-phorophoricacid ester such as diphenyl(2-ethylhexyl)phosphate,diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethylphosphate, diphenyl neopentyl phosphate, pentaerythritoldiphenyldiphosphate or ethylpyrocatechol phosphate;

Alkali metal salt such as melamine polyphosphate, tripolyphosphoricacid, pyrophoric acid, orthophosphoric acid or hexamethaphosphoric acid,phosphoric acid-based compound such as phytic acid, and alkali metal oralkanolamine salt thereof.

Furthermore, as the phosphorus-based compound other than above, thereare applicable phosphorus-based compounds which are used in knownflame-retardant and antioxidant for resins.

The content of the phosphorus-based compound in the thermoplastic resinmolded article is preferably in a range from 0.1 to 30 parts by mass to100 parts by mass of the thermoplastic resin, more preferably from 0.1to 20 parts by mass, and most preferably from 0.1 to 10 parts by mass.

The plated resin molded article prepared by applying the method of thepresent invention provides the adhesion between the thermoplastic resinmolded article and the metallic plating layer, (JIS H8630) of preferably10 kPa or more as the maximum value, more preferably 50 kPa or more asthe maximum value, most preferably 100 kPa or more as the maximum value,and most preferably 150 kPa or more as the maximum value.

The plated resin molded article obtained by the manufacturing method ofthe present invention can select the shape of the plated resin moldedarticle, the kind of plating layer, the thickness of the plating layer,and the like depending on the uses, thus allowing applications invarieties of uses. In particular, the plated resin-molded articleaccording to the present invention is suitable for the automobile partssuch as bumpers, emblems, wheel caps, interior parts, and exteriorparts.

EXAMPLES Adherence Test of Plating Layer

The adhering strength (the highest value) between the resin moldedarticle and a metal plating layer was measured according to theadherence test method described in appendix 6 in JIS H8630 using theplated resin molded articles obtained in Examples and ComparativeExamples.

(Components in the Thermoplastic Resin Molded Article)

A-1 Polyamide (polyamide 6, UBE nylon 6 1013B, water absorption 1.8%,manufactured by Ube Industries Ltd.)

B-1 ABS resin (styrene 45% by mass, acrylonitrile 15% by mass,polybutadiene-based rubber 40% by mass, water absorption 0.2%)

B-2 AS resin (styrene 75% by mass, acrylonitrile 25% by mass, waterabsorption 0.2%)

B-3 Acid-modified ABS resin (styrene 42% by mass, acrylonitrile 16% bymass, rubber 40% by mass, methacrylic acid 2% by weight, waterabsorption 0.2%)

C-1 Dipentaerithritol Examples 1 to 4

The respective components given in Table 1 were blended in a V-shapetumbler, which were then melted and kneaded in a twin-screw extruder(TEX30, cylinder temperature 230° C., manufactured by The Japan SteelWorks, Ltd.) to prepare pellets. The pellets were fed to an injectionmolding machine (cylinder temperature 240° C., mold temperature 60° C.)to form molded articles of 100×50×3 mm in size. The molded articles weretreated as the test pieces for electroless plating in accordance withthe following procedure, thus obtained the plated resin molded articles.The adhering strength of the plating layer on these plated resin moldedarticles is given in Table 1.

(1) Degreasing Step

The resin molded articles were immersed in a 50 g/L aqueous solution (asolution temperature of 40° C.) of ACECLEAN A-220 (manufactured by OKUNOPharmaceuticals Co., Ltd.) for 5 minutes.

(2) Etching Step

The resin molded articles were immersed in an aqueous solution of 200ml/L (2.3 N) of 35% by weight of hydrochloric acid (a solutiontemperature of 40° C.) for 5 minutes.

(3) Catalyst Imparting Step

The resin molded articles were immersed in a mix aqueous solution (asolution temperature of 25° C.) of 150 ml/L of 35% by weight ofhydrochloric acid and 40 ml/L aqueous solution of Catalyst C(manufactured by OKUNO Pharmaceuticals Co., Ltd.) for 3 minutes.

(4) Direct Plating Step

The resin molded articles were immersed in a selector liquid having thefollowing composition (at 45° C. and pH 12) for 3 minutes to form theelectrically conductive layer on the surface of the resin moldedarticle.

Copper(II) sulfate 3 g/L

Sodium hydroxide 30 g/L

Glucose 10 g/L

Hydantoin 10 g/L

(5) Electroplate Step of Copper

The resin molded articles were immersed in the plating bath having thefollowing composition (a solution temperature of 25° C.), andelectroplate was carried out for 120 minutes.

(Composition of Plating Bath)

Copper sulfate (CuSO₄.5H₂O): 200 g/L

Sulfuric acid (98%): 50 g/L

Chlorine ion (Cl⁻): 5 ml/L

TOP LUCINA 2000 MU (manufactured by OKUNO Pharmaceuticals Co., Ltd.): 5ml/L

TABLE 1 Examples 1 2 3 4 (A) A-1 60 60 40 40 (B) B-1 30 30 50 50 B-2 B-310 10 10 10 (C) C-1 10 10 Adhering 85 110 50 60 strength (kPa) (A)-(B):total 100% by mass (C): parts by mass to 100 parts by mass of the sum of(A) and (B)

The appearance of the molded articles in Example 1 to 4 is smooth andbeautiful.

Comparative Example 1

With the same thermoplastic resin molded articles to those in Example 2,the following-given steps without containing the direct plating methodwere applied to prepare the plated resin molded articles. The maximumvalue of the adhering strength of the plated resin molded articles was100 kPa, giving smooth and beautiful appearance. However, themanufacture consumed large man-hours compared with that in Example 2.

(1) Degreasing Step

The test piece was immersed in a 50 g/L aqueous solution (a solutiontemperature of 40° C.) of ACECLEAN A-220 (manufactured by OKUNOPharmaceuticals Co., Ltd.) for 20 minutes.

(2) Contact Treatments Step with an Acid

The test piece was immersed in 100 mL 1.0 N hydrochloric acid (liquidtemperature=40° C.) for 5 minutes.

(3) Catalyst Imparting Step

The test piece was immersed in a mix aqueous solution (a solutiontemperature of 25° C.) of 150 ml/L of 35% by weight of hydrochloric acidand 40 ml/L aqueous solution of Catalyst C (manufactured by OKUNOPharmaceuticals Co., Ltd.) for 3 minutes.

(4) The First Activation Step

The test piece was immersed in 100 ml/L aqueous solution (a solutiontemperature of 40° C.) of 98% by weight of sulfuric acid for 3 minutes.

(5) The Second Activation Step

The test piece was immersed in 15 g/L aqueous solution (a solutiontemperature of 40° C.) of sodium hydroxide for 2 minutes.

(6) Electroless Plating Step of Nickel

The test piece was immersed in a mix aqueous solution (a solutiontemperature of 40° C.) of 150 ml/L of Chemical Nickel HR-TA(manufactured by OKUNO Pharmaceuticals Co., Ltd.) and 150 ml/L ofChemical Nickel HR-TB (manufactured by OKUNO Pharmaceuticals Co., Ltd.)for 5 minutes.

(7) Acid Activation Step

The test piece was immersed in 100 g/L aqueous solution (a solutiontemperature of 25° C.) of TOP SAN (manufactured by OKUNO PharmaceuticalsCo., Ltd.) for one minute.

(8) Electroplate Step of Copper

The test piece was immersed in the plating bath same to that of Example1 (a solution temperature of 25° C.), and electroplate was carried outfor 120 minutes.

1. A method for manufacturing a plated resin molded article, comprisingthe steps of: contact-treating a thermoplastic resin molded article withan acid or base being free from heavy metal; treating thecontact-treated thermoplastic resin molded article with acatalyst-imparting liquid; forming an electrically conductive layer onthe surface of the thermoplastic resin molded article by direct platingmethod; and applying electroplating to the electrically conductivelayer; without any etching step by an acid, which contains heavy metal.2. The method for manufacturing plated resin molded article according toclaim 1, wherein the direct plating method comprises the step of formingan electrically conductive layer on the surface of a thermoplastic resinmolded article with a selector liquid which contains a metal compound, areducing compound and a metal hydroxide.
 3. The method for manufacturingplated resin molded article according to claim 1, wherein thethermoplastic resin molded article comprises a polyamide.
 4. The methodfor manufacturing plated resin molded article according to claim 1,wherein the thermoplastic resin molded article further comprises asubstance which has a solubility (23° C.) in water of 300 g/100 g orless.
 5. The method for manufacturing plated resin molded articleaccording to claim 1, wherein the thermoplastic resin molded articlecomprises a polyamide, and further a substance which has a solubility(23° C.) in water of 300 g/100 g or less.